I think most light boats are right-hand drive (I've been told) so that the weight counters the torque of the prop when the boat's going to plane. I don't know how accurate that is.
As for helicopters; most have a right-hand pilot because a) the collective is in the pilot's left hand and b) you never, ever take your hand off the cyclic when the 'copter is moving. That places the hand free to work in the center of the cabin; where it has access to the controls. That's what I've been taught anyway.